Huntree Newsletter Boxwood Blight

We have just become aware that Boxwood Blight has appeared in our community.   It is a devastating fungus.  We are very distressed about this.  This week a homeowner has come in with a diagnostic report from MSU concluding that their Boxwoods do have Boxwood Blight.  We are alarmed!

Read the following to familiarize yourself with the symptoms of this fungal pathogen and inspect your Boxwoods.

Symptoms:

• Brown leaf spots that lead to defoliation
• Black streaking on the stems
• Leaves turning brown
• Leaves falling off the plant in great numbers

The symptoms usually appear in late summer and fall.

Wet foliage favors this disease. Avoid overhead irrigation.

Ensure good air circulation in planting beds by providing adequate spacing between plants.     (Three homeowners who have determined to have blight have a large concentration of many Boxwoods planted in tight spaces and trimmed tightly. )

Once blight infection begins, it cannot be effectively controlled.

Remove the affected plants, placing them in bags and sending them to the landfill.  Do not compost them or leave them in the yard.  Also clean up any dead leaves laying around on the ground.  Place them in a plastic bag and send them to the landfill as well.  Burning is also an acceptable method of disposing.

Do not let anyone prune your Boxwoods without sterilizing pruning tools before and after. Use a solution of: 1 part bleach to 9 parts water or 1.25 oz Lysol Concentrate Disinfectant to 1 gallon water.  At least 5 minute contact time is recommended for tools. These products are corrosive, so oil tools after treatment. At least 10 minutes for pots or other surfaces.

Place two to 3 inches of mulch under existing plants to prevent splashing water from spreading the spores.

Prevent stress to your Boxwood.   Do not overwater.  Boxwoods do very well in dryer soils.

Do not use overhead watering methods.   (Watering multiple times a week is not a good idea!)

Spores can remain in the soil for 5 or 6 years after removal of affected plants.  Do not replant Boxwoods in same location.

To protect existing Boxwood which have no symptoms, fungicides may be applied to prevent spread of spores.  Apply beginning in spring when daytime temps are between  60 and 80 degrees and prolonged rain is predicted.   Spray every 7 to 14 days.

Effective products are chlorothalonil (Daconil), propiconazol + chlorothalonil, and chlorothalonil + thiophanate-methyl (Spectro 90 WDG).

Do not use Boxwood branches for Christmas decorations.

(Not all brown leaves on Boxwoods are blight.  Leaf miner is an insect causing bubble-like lesions on the leaf which turns brown, so inspect the leaves before you jump to the wrong conclusion.)

Go online to Virginia Tech:  Boxwood blight to see pictures.

If you want to have a sample diagnosed, go to the MSU diagnostic lab website:

MSU Plant & Pest Diagnostics

East Lansing, MI   517-355-4536

www.pestid.msu.edu

Give us a call if you have questions.

Jan

And the Huntree Gang

Categorised in: Newsletter

This post was written by MHarrison9